In part, the quality of audio that is played back to a listener depends on how the audio was recorded and how the audio was compressed/decompressed (if at all). A playback device can sometimes perform processing during playback, however, to improve the listening experience.
One way of improving the listening experience when the listener is using headphones is to provide a surround experience. Due to the nature of headphones, which typically place speakers next to, or pushed into, the listener's ears, the sound field created by the headphone speakers is perceptually centered close to, or inside, the listener's head. This can be an undesirable result of listening to audio using headphones.
Some existing headphone surround techniques can provide a surround sound experience using long finite impulse response (FIR) filters. However, long FIR filters, even with fast Fourier transform (FFT) based block convolution, can be prohibitively complex for implementation on low power, or resource-constrained, devices.
Other existing headphone surround techniques can provide a surround sound experience using head related transfer functions (HRTFs). However, HRTFs can be difficult to implement and can require significant computing resources. For example, HRTFs can be difficult to tailor to provide a surround experience for all, or a majority of, listeners.
Therefore, there exists ample opportunity for improvement in technologies related to creating a surround experience for headphones.